1. Field of the Invention
This invention relates to High Performance Liquid Chromatography (HPLC) and more particularly, this invention relates to a pneumatically- and/or hydraulically-actuated preparation and purification method and system that operates in harsh environments and with harsh reagents.
2. Background of the Invention
Enhanced chromatographic techniques are required for investigations in biosciences, environmental sciences, nuclear chemistry and geochemistry. Traditional gravity driven (open column) chromatography, while clean and corrosion resistant, suffers from significant limitations pertaining to the overall length of column and resin size, and are time inefficient as they require multiple passes in order to achieve adequate separation of constituents (e.g., Ni and Mg).
High-performance liquid chromatography (HPLC) overcame many of these limitations (e.g., a closed-system setup involving the ability to pressurize the system, which allows for longer columns, finer resin-size and better separations; basically a semi-automated set-up). However, they are not sufficiently corrosion resistant and are thus not suitable to handle the highly corrosive reagents necessary to effect clean separations of certain compounds and elements. Two major causes of problems are the following: 1) the liquid flow path often contains glass, metal or non-resistant plastic parts that are corroded/dissolved by concentrated acids or organic solvents, leading to contamination of the samples, and 2) the electronic controls are often in close spatial relationship with the HPLC unit, drastically shortening the lifespan of the apparatus as the metallic parts rapidly corrode in these harsh chemical environments.
Some gas chromatographs use pressure as both the actuation medium and the signal to trigger the next step of the process in a force-feedback reaction chain in order to isolate one or more desired gas species from bulk gas. A motivation to such developments was avoiding explosion of flammable gases in contact with an ignition source. In such systems, the sample and carrier gases flow under their own pressure, they mix spontaneously, and only one inert carrier gas is used at once. Also, many of these systems rely on a complex assemblage of interconnected “logic elements” (e.g., metal-based mechanical parts producing various output signals from respective inputs signals). It is this assemblage that is susceptible to corrosion and other harsh environs of HPLC protocols.
Liquid chromatographic separation processes are often performed in laboratory spaces where fumes of corrosive solvents are permanently present, thus containment of the separation columns alone do not protect the electronic units or any exposed parts that are not chemically resistant. Moreover, the processing schemes are more complex in liquid chromatography than in gas chromatography, in that several corrosive liquid reagents often have to be used in combination, pumped with a precise mixing proportion, actively mixed through stirring or other means to overcome differences in densities and viscosities, and forced through the column by means external to the liquid of interest. The eluents are often chemically and/or physically unstable, requiring timely and frequent preparation. Due to this complexity, HPLC systems necessitate sophisticated computer software that offer more flexibility to rapidly modify elution characteristics, rather than logic elements hardware used in pneumatic gas chromatography.
A need exists in the art for a High Performance Liquid Chromatography method and system which can withstand highly corrosive reagents and operating environments. The method and system should rely on as few electronic components as possible so as to minimize corrosion damage to the components, yet should be apt to full automation via computer software.